As the demand for improved inspection capabilities continues to increase so too will the demand for improved image sensor devices. Typically, inspection systems utilize area sensors equipped with multiple readout registers per sensor, whereby each readout register sequentially outputs 16, 32 or more columns. A typical inspection system may use one or two sensor arrays in this regard. The image sensors included in current inspection technologies typically include charge-coupled devices (CCDs) due to their low noise and high quantum efficiency. In addition, a typical sensor array may be back-thinned and illuminated from the back, so as to maximize quantum efficiency, which is particularly advantageous at short (deep UV) wavelengths. A typical array sensor may consist of a few hundred to a few thousand pixels along each side of the sensor. Pixel dimensions are typically on the order of between about 10 μm and about 20 μm.
Typically, each image sensor is mounted on, or connected to a circuit board. The circuit board may contain drivers for driving the various clock and gate signals, amplifiers, double correlated sampling circuits and digitizers for converting the analog signals to digital signals. The circuit board may also include transmitters for transmitting the digital signals to associated image processing computers. In some cases, up to 16 digitizers may be mounted inside an assembly with an image sensor in order to help reduce the capacitance between the outputs of the sensor and the inputs of the digitizer as compared with mounting the digitizers on the circuit board. The inspection systems of the prior art, however, are limited in speed to an order of 109 pixels per second, with scaling capabilities approaching 1010 pixels per second. Continued scaling beyond this level is not practical. As such, it is desirable to cure the defects of the prior art and provide methods and systems capable of extending to the speed of image sensor array based inspection technologies.